Ladders are common tools for climbing high for fetching something or for maintenance in daily life. Ladders are roughly classified into two categories. One category is straight ladders. Such a ladder comprises two upright poles and cross rails erected between the two upright poles. These ladders may be used vertically only. The ladders need to be leaned against a fixed position to support the ladders when in use. Moreover, the ladders have a single function of climbing high. If such ladders are used for maintenance, a person has to climb up and down the ladders to pick up or put down tools for many times, so that it is very inconvenient. Another category is herringbone ladders. Majority of such ladders consist of a main ladder frame and a support ladder frame, which are hinged together on their tops. Compared with the straight ladders, the herringbone ladders can support climbing operations overhead.
Existing ladders have no large working platform on their tops, so they cannot be used as a working platform. A working platform allows a user to perform operations such as sawing, cutting or carving on this platform.
A Chinese Patent CN202125241U, entitled WORKING PANEL AND WORKING PLATFORM LADDER WITH SAME, has disclosed a ladder capable of serving as a working platform. The ladder comprises three ladder frame segments. Each of the ladder frame segments comprises two opposite side rails arranged at intervals, and a number of cross rails arranged between the two side rails. The side rails of two adjacent ladder frame segments are rotatably connected together by a hinge mechanism. Support legs are provided on the bottoms of two outermost ladder frame segments, respectively. A working panel is placed within the middle ladder frame segment to form a working platform. Although the ladder may serve as a working platform, a dependent working panel needs to be additionally provided; and the working panel is separated from the ladder so that the working panel may be easily lost or left behind